The authors of the present study report treatment experience of acute myopia and branch retinal vein occlusion associated with phendimetrazine, a drug used for weight reduction.

Case 1: A 32-year-old woman, previously devoid of ocular problems, visited our hospital with bilateral visual disturbance after taking phendimetrazine for weight reduction. Ciliochoroidal effusion and anterior shifting of the lens-iris diaphragm were observed, which resulted in a shallow anterior chamber, myopic shifting and an increase in intraocular pressure due to angle closure. The symptoms were relieved by discontinuing the use of phendimetrazine and administration of intraocular pressure-lowering agents. Case 2: A 26-year-old woman, previously devoid of ocular problems, visited our hospital with left superior visual field disturbance after taking phendimetrazine for weight reduction. The examinations revealed papilledema, disc hemorrhage and tortuous vascular changes in her left eye. Fluorescein angiography was performed, and retinal vein occlusion was diagnosed. The patient discontinued weight reduction agents and recovered while under observation.

Phendimetrazine, used for weight reduction, can cause acute myopia via prostaglandin synthesis and retinal venous occlusion due to vascular constriction.